Toroidal electromagnetic deflection yoke

ABSTRACT

A toroidal deflection yoke is provided for a delta gun shadow mask color television picture tube. The wire distribution of the horizontal and vertical deflection coils is determined by selecting a minimum number of design parameters in the form of angular distributions of windings which can be varied for producing a deflection yoke which yields optimum performance in electron beam convergence and registration.

United States Patent Chiodi i [54] TOROIDAL ELECTROMAGNETIC DEFLECTION YOKE [72] Inventor: Wayne Richard Chiodi, Indianapolis, Ind.

[73] Assignee: RCA Corporation [22] Filed: June 3, 1970 [21] Appl. No.: 42,927

Related U.S. Application Data I63] fgginuation-in-part of Ser. No. 805,276, Mar. 7,

[52] U.S.Cl ..335/2l3,3l3/75 [Sl] lnt.Cl.

[58] FieldoiSearch ..33'5/2l0,2l3;3l3/75, 76, 77; 315/27, 27 X [56] References Cited UNITED STATES PATENTS 2,925,542 2/1960 Gethmann ..335/2 1 3 .L....H0li 5/00 Feb. 15,1972

3 ,430,099 2/ 1969 Ashley ..3 1 5/27 3,548,350 12/1970 Archer ..335/2l0 FOREIGN PATENTS 0R APPLICATIONS 514,170 I 1/1939 Great Britain ..335/2l0 Primary Examiner-G. Harris Attorney-Eugene M. Whitacre l 5 7 I ABSTRACT A toroidal deflection yoke is provided for a delta gun shadow mask color television picture tube. The wire distribution of the horizontal and vertical deflection coils is determined by selecting a minimum number of design parameters in the form of angular distributions of windings which can be varied for producing a deflection yoke which yields optimum performance in electron beam convergence and registration.

10 Claims, 8 Drawing Figures PATENIEUFEB 15 m2 SHEET 1 OF 3 A T TOP/VF Y PATENTEDFEB 15 I972 SHEET 2 OF 3 IN VliN'l 0k, Wayne R. Chz'odl' B Y Fig.6.

PATENTEDFEB15 m2 3.543.192

SHEET 3 OF 3 HORIZ.WIRES -VERT. WIRES [NV/5N! OR. F M I Wayne R. Chl'odl' BY K ATT'AH- 1 TOROIDAL ELECTROMAGNETIC DEFLEC'IION YOKE This is a continuation-in-part of application Ser. No. 805,276 filed Mar. 7, 1969.

BACKGROUND OF THE INVENTION This invention relates to electromagnetic deflection yokes and particularly to a toroidal deflection yoke for use with a delta gun shadow mask color television picture tube.

l-leretofore, deflection yokes for television receivers have been wound utilizing one of two general methods-toroidal winding and saddle winding. While a yoke made by the toroidal winding method requires less complicated, less costly manufacturing tools as well as a shorter length of active conductors (e.g., less wire) than a comparable yoke made by saddle winding, use of toroidal wound yokes has been confined to monochrome and so called in-line gun color television picture tubes. In the case of the commonly used delta gun, shadow mask color television tube, saddle coils have been employed for both horizontal and vertical deflection windings to satisfy the exacting convergence and registration (purity) requirements of yokes for such tubes. Particularly with regard to large screen delta-gun picture tubes utilizing relatively wide deflection angles such as 110, the difficulty of maintaining satisfactory beam convergence and color purity in the comers as well as the center of the picture tube has required the use of relatively complex dynamic convergence correction circuitry including dynamic blue lateral convergence waveforms to compensate for coma aberrations in the horizontal yoke coil as well as requiring relatively complex yoke driving circuitry incorporating a dynamic difference waveform resulting in an unbalance of current in. each half of the horizontal winding, the unbalance being proportional to the product; of horizontal and vertical scan current.

It is an object of this invention to provide a toroidally wound deflectionyoke having a minimum number of design parameters for producing a yoke yielding acceptable registration and convergence of the electron beams of a delta gun shadow mask picture tube.

It is another object of this invention to provide a yoke having improved electron optical performance without requiring a'difference current driving circuit ordynamic blue lateral convergence correction.

A deflection yoke is provided for a delta gun shadow mask picture tube. The yoke comprises a pair of horizontal and vertical deflection windings wound toroidally around a generally conically. shaped ferrite core, the inside surface of which generally conforms to a flared portion of the picture tube. Each of the vertical-and horizontal windings comprises symmetrical portions in each of four quadrants of the yoke, the quadrants being defined by the vertical and horizontal deflection axes. Each portion comprises at least convolutions of conductors having a first predetermined angular separation from each adjacent conductor in a layer extending throughout a first angular segment along the perimeter of the toroidal yoke from a line of symmetryandconvolutions of conductors having a second predetermined angular separation from each adjacent conductor in a layer extending throughout a second angular segment along the perimeterof the yoke from'the same line of symmetry. Overlapping convolutions provide a desired conductor cross-sectional distribution for achieving acceptable registration and convergence of the electron beams.

In another embodiment utilizing two layers of conductors forforming the horizontal and vertical deflection coils, in each quadrant the yoke conductors in the first layer extend continuously over first and second angles from the respective axes to form first portions of the horizontal and vertical coils. Conductors in the second layer extend over a first angle, are separated over a second angle and extend over a third angle measured from one axis for forming other portions of one of the coils, and conductors extend over a fourth angle measured from the other axis and within the separation of the aforementioned second angle for forming further portions of the other of the coils, the respective portions in both layers of the four quadrants being interconnected for forming the horizontal and vertical deflection coils.

For a more complete disclosure of the invention reference may be had to the following description which is given in conjunction with the accompanying drawings of which:

FIG. 1 is a view, partly broken away and partly in section, of a delta gun shadow mask picture tube and a toroidally wound deflection yoke according to the invention;

FIG. 2 is a perspective view of the toroidally wound deflection yoke of FIG. 1;

FIG. 3 illustrates the variable design parameters utilized in determining the conductor distribution of the yoke;

FIG. 4 illustrates-a typical winding distribution at the rear of a toroidally'wound yoke according to the invention;

FIG. 5 is a partial view illustrating a typical winding distribution at the front of a toroidally wound deflection yoke according to the invention;

FIG. 6 is a, schematic representation of the vertical and horizontal windings of the toroidal yoke illustrated in FIG. 4;

FIG. 7 illustrates a winding distribution of conductors at the rear of another toroidally wound yoke embodying the invention; and

FIG. 8 is a schematic representation of the vertical and horizontal coil windings of the toroidal yoke illustrated in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a toroidally wound deflection yoke 20 mounted adjacent the flared bulb section of a delta gun shadow mask tube 1]. Tube 11 comprises an evacuated glass envelope 12 having a faceplate 13 at the front viewing portion of the picture tube. Red, blue and green phosphor dots 14 are disposed on the inside surface of the faceplate l3. Mounted within picture tube 11 is a shadow mask 15 having apertures 16. The rear portion of picture tube 11 contains delta electron gun structure 17, the three beams from which are directed along the tube 11 and through apertures 16 to excite the color phosphors 14.

A toroidally wound deflection yoke 20 encircles the flared bulb section of picture tube 11, the inside surface of which yoke generally conforms to the contour of the flared bulb section and is mounted adjacent the flared bulb section. Yoke 20 comprises approximately conical ferrite core 22 having circular cross section around which are toroidally wound conductors 21 (see FIG. 2). Mounted around and adjacent the rear and front portions of ferrite core 22 are grooved rings 23 and 24, respectively. The rings may be made of plastic, for example. The grooves in rings 23 and 24 serve to maintain the desired spacing between the toroidally wound wires. Current in that portion of conductors 21 conforming to the inside surface of ferrite core 22 produces the magnetic field for deflecting the electron beams horizontally and vertically to scan a raster on the faceplate 13. The return portions of conductors 21 are stretched between the front and rear rings 24 and 23 on the outside of core 22.

FIG. 2 is a perspective view of yoke 20 illustrating grooves 25 in the front plastic ring 24. The grooves are spaced equally distant from each other around the front surface of ring 24. In one illustrative embodiment, the spacing of the grooves is 1. It is to be understood that the rear ring 23 fitted over the rear portion of core 22 also may contain the grooves spaced at equal angles from each other around the reannost surface of ring 23. In the illustrative embodiment, the grooves or rear ring 23 are spaced every 2. Also illustrated in FIG. 2 are a number of convolutions of conductors 21 extending through the core 22 and conforming to the inside surface thereof. The return portion of conductors 21, although not shown, is stretched between front and rear grooved rings 24 and 23 as illustrated in FIG. I. The conductors 21 are toroidally wound around core 22 with conventional apparatus of the type presently employed for winding toroidal yokes. A first layer or course of conductors 21 is wound around core 22 such that the conductors occupy every other groove on the front grooved ring 24 and, in the illustrated embodiment, occupy every groove on the rear ring 23. Thus, each conductor of the first layer is spaced 2 from the next adjacent conductor of that layer. A second layer or course of conductors 21 is then wound around the core 22 such that the conductors of the second layer fill the remaining grooves of front grooved ring 24 and overlap portions of the first layer at the rear ring 23 (see FIG. 3). Thus, each of the first and second layers will have conductors 21 spaced 2 apart around the core 22. Conductors of the first layer are offset from adjacent conductors of the second layer by 1. The yoke will then appear to contain conductors spaced-apart l from adjacent conductors.

The term layer" as used herein refers to that portion of a conductor which is wound around the core 22 in one complete circumferential traverse (360) of the core 22 by the conductorwire. I w I w, p g M W Once the two layers of conductors have been wound, separate horizontal and vertical coil windings are formed by cutting, peeling, and interconnecting appropriate conductors of thetwo 360 layers in a manner to be described subsequently W FIG. 3 illustrates the angular distribution of conductors is the same at each cross section at any point along the longitu-- dinal (Z) axis of core 22. Core 22 of FIG. 3 is shown to be segmented by X- and Y-axes 26 and 27 into four quadrants indicated by the numerals I, II, III and IV. Conductors 21a form a first winding of conductors as described in connection with FIG. 2 and conductors 21b form a second winding of conducto r s also described in FIG. 2.

For the purposes of describing the invention which is directed to the distribution of windings around core 22, only the distribution of wires within quadrant I, bounded by the X-. and Y-axes, will be described. It is to be understood that the windings in each of the quadrants I, II, III and IV are similar qthe sva reet ers s mmet cal.

Illustrated in quadrant I F FIG. 3 is a layer of conductors 21a extending from the X-axis through an angle 0, and a second layer of conductors 21b extending through an angle 0 from the X-axis. In this embodiment, the conductors 21a and 21b have the same arcuate spacing. Each conductor the quadrants of the toroidal deflection yoke contains both vertical and horizontal windings. The method of determining the distribution of conductors for each of these windings is similar so the invention will be described in connection with FIG. 3 with regard to the general case of determining conductor distribution. In designing the toroidal deflection yoke the diameter and length of the yoke (i.e., the core 22) once initially selected, are not regarded as variables. g

It has been determined that, for each of the horizontal and vertical deflection windings, acceptable registration and convergence can be obtained by distributing conductors for each such winding in a first layer along an angular segment 0, and in a second layer along an angular segment 0, with respect to a reference axis in each quadrant. The angles 0, and 0, for each of the horizontal and vertical deflection windings may be determined by arbitrarily selecting a plurality of sets of values 60 of such parameters, winding yokes according to such selected values, measuring resultant convergence and/or registration errors at the faceplate of a picture tube, and by mathematical analysis, calculating values for such parameters whereby the specified errors are minimized. It should be noted that several performance factors can be optimized by varying the minimum parameters, but since convergence is affected most by conductor distribution, it will be shown how to determine the optimum parameters with special attention being given to minimizing v en was r t Convergence errors can be minimized by manipulating only four parameters (0 0 0, 0 and these same parameters completely describe the conductor distribution of the yoke. This fundamental relationship between yoke performance (minimum misconvergence) and conductor distribution is expressed by the following general equation:

in which f is the convergence error under consideration and the angles are considered as independent variables. A linear approximation can be made such that for small misconvergence errors f and Af the partial quantities of equation (I) may be replaced by' constants, and a linear equation, as follows, will be valid in the vicinity of the various angles: (2)

wmmwm. raw r in which the constants are af, bf, cf, df and ef, ef being a constant of integration.

The five constants of equation (2) can be determined by selecting five sets of angles (0, 0 0 0 winding five 5 corresponding yokes, measuring the resultant convergence mounted, and the five linear equations (2) are solved for the constants. It may be desirable to set up more than five yokes so that the influence of any measurement error is minimized. In this situation a least square error solution is obtained to yield the correct constants. The constants obtained are then 30 used to determine the 0 angles of equations (2) such that f (the error) equals zero. A second set of yokes are then wound having the angular conductor distribution extending over the 0 angles derived from the last operation. This process may be repeated, using the derived data from one set of yokes as the design data of a succeeding set of yokes until the optimum performance (minimum misconvergence) conductor distribution is achieved. Such a repeating process is known as a recursion scheme. It is essential in designing a yoke to solve simultaneously for minimization of a multitude of convergence er- 40 rors in which case the above scheme may be readily extended to accomplish this by the use of matrix equations.

Referring now to FIG. 4, a typical conductor distribution at v the rear of the toroidal yoke is shown. The yoke is shown divided into four quadrants I, II, III and IV by horizontal and vertical deflection axes 26 and 27. The conductor distribution in each of the quadrants is identical. For convenience, the conductors of the horizontal deflection winding are indicated by Xs and the conductors of the vertical winding are represented by circles. The number of conductors shown are 501 illustrative only and it is to be understood that in actual practice the conductors would be smaller and greater in number. Referring generally to FIG. 4, it can be seen that there is a first layer of conductors 21a wound around the core 22 and a second layer of conductors 21b similarly wound around core i 22. Conductors 21a are wound such that they are spaced 2 from each other. This spacing is maintained by the use of the grooved rings described in connection with FIG. 2. The second layer comprising conductors 21b is wound such that the conductors 21b lie in the grooves formed by conductors j. 21a of the first layer. Thus, the spacing of conductors 21b is also 2 but the entire second layer is offset 1 from the first layer.

In quadrant I of FIG. 4 the distribution of horizontal conjductors is illustrated. This distribution comprises a first number of conductors spaced-apart 2 and extending through an angle 0, and a second number of wires spaced-apart 2and extending through an angle 0 Thus, it can be seem that the portion of the horizontal deflection winding in quadrant I comprises a step function of two steps of conductors extending through angles 0, and 0 That portion of the quadrant in which the two steps i.e., 0, and 0 overlap, results in a higher conductor density than that portion where only the conductors from the 0, step are present. Referring generally to FIG. 4.

it can be seen that the horizontal winding portions are symmetrically in each quadrant about the horizontal axis 26.

Referring to quadrant II of FIG. 4 the distribution of a portion of the vertical deflection winding is illustrated. This distribution comprises a first number of conductors spaced-apart 2 and extending through an angle starting from the vertical axis 27, and a second number of conductors spaced-apart 2 and extending through an angle 0 starting from the vertical axis 27. It can be seen that in the portion of the quadrant where the two angles 0 and 02 overlap that the conductors density is greater than in that portion of the quadrant containing only the wires of the 0 function. Referring generally to FIG. 4, it can be seen that the vertical deflection winding comprises symmetrical portions in each of the quadrants about tee vertical axis 27.

Referring to quadrant II of FIG. 4, wires 21c and 21d are shown on the outside perimeter of core 22. Wires 21c are the return wires for the active conductors 21a and 21d are the return wires for the active conductors 21b. It is to be understood that these return wires extend around the entire perimeter of core 22.

FIG. 5 illustrates the wire distribution at the front end of the yoke. As can be seen clearly in FIGS. 1 and 2, the yoke 20, mounted adjacent the flared bulb section of the picture tube has a front end portion which has a greater diameter than the rear end portion. Therefore, with the same angular spacing between the conductors at the rear end and front end portions of the yoke, it can be seen that the conductors will have a greater-linear spacing around the perimeter at the front of the yoke than at the rear of the yoke. For this reason, the conductors at the front of the yoke do not form one layer on top of another but rather, as shown in FIG. 5, form a single-layer comprising alternate conductors 21a and 21b. The spacing betweenthe conductors 21a is 2 and the spacing between the conductors 21b is 2", the same angular spacing exits at the rear of the yoke. Wires 210 at the outside perimeter of core 22 are the return wires for active conductors 21a and wires 21d are the return wires for active conductors 21b. It is to be understood that the conductors shown in FIG. 5 extend around the perimeter of core 22.

The individual conductors indicated by capital letters in the four quadrants of FIG. 4 represent the start and finish of the various horizontal and vertical winding portions in each of the quadrants.

FIG. 6 is a schematic representation of the horizontal and vertical coil windings formed by the portions of these windings in the four quadrants of FIG. 4. The letters of FIG. 6 indicate which portions of the horizontal and vertical windings of FIG. 4 are electrically interconnected to form the complete horizontal and vertical windings.

One example of a yoke constructed according to the invention and used successfully with an RCA-type l5NP22, I5

inches diagonal, 90 delta gun shadow mask color picture tube is as follows, referring to FIG. 4 for orientation:

Wire used: No. 23 copper, wound on a flared ferrite core having a 2.2 inches length, 1.68 inches small end inside diameter and 4.0 inches inch large end inside diameter, the core having a thickness of 0.3 inch.

0, 70 (35 convolutions) 0 7 (4 convolutions) 0 77 (39 convolutions) 0 y, 18 (9 convolutions) Although the specific embodiment described utilized only two parameters, i.e., 0 and 0 for each portion of the horizontal and vertical deflection coil windings, is to be understood that three of more parameters corresponding to three or more stairsteps may be used as required to permit the necessary freedom of design in determining the conductor distribution ofany particular yoke.

Also, as illustrated in the described embodiment, only two initial layers of wires were wound toroidally around the core. It will be appreciated that even though only two parameters were selected for determining the distribution of conductors, these two parameters (0, and 0,) may extend over such relatively large angles in each quadrant that the individual conductors might overlap in three layers. This would be of little consequence as in actual practice the wires are so small in diameter in relation to the front and rear diameters of the yoke that the overlapping layers do not adversely affect yoke performance.

As previously mentioned the problems of maintaining good beam registration and convergence in delta gun color television systems increase as tubes employing larger beam deflection angles and viewing areas are utilized. As a practical matter it is desirable to limit the toroidal deflection yoke windings to no more than two layers of conductors as it becomes more difficult to lay down a third layer and maintain the proper relationship of the conductors in each layer one to the other. It has been found that a two layer yoke embodying the invention maybe utilized in conjunction with wide angle large screen color picture tubes such as a tube having a beam deflection angle of by building the yoke with an additional design parameter. This additional design parameter to be described subsequently permits a two layer toroidal yoke to be satisfactorily utilized with large screen, wide deflection angle picture tubes.

The additional parameter which gives greater design freedom for minimizing beam landing aberrations comprises one or more conductors of one of the coils disposed in such a location in each quadrant of the yoke that convergence and registration can be maintained throughout the raster while maintaining minimum coma in the horizontal coil. These additional conductors may be considered as providing a relatively small perturbation of the two layer winding described in the first-described embodiment. It is necessary that these additional wires be accurately located such that they do not degrade one performance characteristic provided by the yoke, in particular, coma in the horizontal coils, while improving other performance characteristics, such as corner convergence and registration. The angle about which the conductors must be placed to accomplish this may be called the coma invariant angle of the horizontal coils. FIG. 7 illustrates a winding distribution of conductors at the rear of a toroidally wound deflection yoke including the additional winding parameter discussed above. The coils may be wound on the yoke in a conventional manner by winding two layers of conductors around the yoke and then appropriately peeling and interconnecting conductors as shown in FIGS. 7 and 8.

Included in the two layers of conductors are conductors 34 representative of the conductors of the horizontal coil and conductors 35 representative of the conductors of the vertical coil. A portion of the return horizontal conductors 34a and return vertical conductors 350 are shown on the outside of ferrite core 31 in quadrant II. The quadrants I, II, III and IV of the yoke are symmetrical about the orthogonal X (horizontal) axis 32 and Y (vertical) axis 33. The angles shown in quadrant I represent the conductor distribution for the horizontal coil in one quadrant; this distribution is the same in all of the quadrants. The angles in quadrant II refer to the winding distribution of the conductors comprising the vertical coil in one quadrant. This distribution is the same in all of the quadrants.

Referring to quadrant I of FIG. 7, the first layer of conductors includes a portion of horizontal conductors 34 having a predetermined angular separation from each other extending throughout an angle 0 from the X-axis 32. In the second layer similar conductors 34 extend over an angle 0 from the X-axis 32. Additionally, further horizontal conductors 34 extend throughout an angle ag-04 measured from the X-axis 32. These additional horizontal turns comprise the perturbation of the horizontal winding for providing optimum registration and convergence while maintaining coma at a minimum. These additional conductors, five in the illustrated embodiment, are centered about a conductor 34c which is disposed at the abovedescribed coma invariant angle. It should be noted that these additional conductors are disposed in a separation of the vertical conductors in the second winding layer.

In quadrant number II vertical conductors 35 having a predetermined angular separation extend over an angle 0 in the first layer measured from the Y-axis 33. Further, vertical conductors 35 in the second layer extend over an angle measured from the Y-axis 33. A separation is provided in the vertical conductors extending over an angle O -O measured from the Y-axis 33. Additional vertical conductors in the second layer extend over an angle G -0 measured from the Y-axis 33. It should be noted that the horizontal conductors 34 centered about the coma invariant angle are disposed in the second layer within the separation of the vertical conductors 35. 7

FIG. 8 illustrates schematically the interconnection of the vertical and horizontal coil portions contained within the first and second layers shown in FIG. 7 for forming the desired vertical and horizontal deflection coils of the yoke. The capital letters in FIG. 8 are referenced to capital letters indicating the end conductors of portions of the respective horizontal and vertical coil portions shown in FIG. 7.

The following discussion relates to the coma invariant angle mentioned above. Horizontal coil coma aberrations, or inappropriate width of the blue raster as the picture tube electron beam is scanned over the inside of the viewing screen along the horizontal center line, is related to the yoke parameters by equation (2) above, in which (f) corresponds to the blue width aberration.

By transforming the independent set of step angle variables (0, 0 0 0 y) to its unique counterpart set of moment angle variables (M M M M (to be explained subsequently) and then by applying the aforementioned recursion scheme to optimize over the set of moment angle variables, a relation analogous to equation 2 is obtained for any of th multitude of aberrations to be minimized.

m+ uF w+ w in which W is the blue width aberration, M and M are the first and second moments of the cross section of the deflection yoke conductor distribution, and a, b, c, d and e are the constants obtained from the above described recursion scheme.

The first moment (M in each quadrant may be considered the center of gravity of a transverse cross section of the coil conductors and is expressed by the following equation:

in which n is the total number of wires per quadrant of the horizontal coil under consideration and 0, is the angle location of the 1''" wire as measured from the horizontal axis of symmetry.

The second moment (M in each quadrant may be considered the spread of conductors about the first moment given in (4) above and is expressed by the equation:

Finally, the coma invariant angle (0 may be derived from equations (3 (4) and (5) and is expressed by the equation:

utilized further in the embodiment described in conjunction with FIG. 7.

Once the coma invariant'angle is determined for a particular coil in a yoke there is some freedom in the amount of conductors to be added around this point. The exact number can be determined empirically by observing the performance of the yoke as the wire is added. As long as the number of added conductors is small relative to the total number of conductors the coma will not be adversely affected. It should be noted that in the described embodiment it was necessary to separate the vertical turns in order to accommodate the additional horizontal turns. Referring to FIG. 7, it can be seen that the vertical conductors are separated in the area of least concentration of vertical conductors. With this arrangement the coil parameters can be readily optimized to their final values by use of the optimization scheme described in conjunction with FIG. 4.

lclaim:

1. A toroidally wound deflection yoke for a delta gun shadow mask color television picture tube for providing convergence of the beams in the comers of a raster displayed on said picture tube, comprising:

a cylindrical core having the inside portion thereof flared to conform generally with a flared portion of said picture tube,

a pair of horizontal and vertical windings wound toroidally around said core for deflecting the electron beams of said tube upon energization of said windings, each of said vertical and horizontal windings comprising symmetrical convolutions of wire in each of the quadrants of said yoke, forming portions of said vertical and horizontal windings therein, said quadrants being defined by the vertical and horizontal axes of deflection,

each of said portions of said vertical and horizontal windings in each of said quadrants comprising at least convolutions of wire having a first predetermined angular separation from each other extending continuously throughout a first angular segment along the perimeter of said core from a line of symmetry of said quadrant and convolutions of wire having a second predetermined angular separation from each other extending continuously throughout a second angular segment along said perimeter from said line of symmetry, said first and second angular segments being selected for producing a magnetic field which provides convergence of the beams in the cornets of said raster.

2. A toroidally wound deflection yoke as defined in claim 1 wherein said first and second angular segments are different whereby the conductor distribution density is higher in that portion of the quadrants wherein said first and second segments overlap than in that portion of the quadrants wherein said angles do not overlap.

3. A toroidally wound deflection yoke as defined in claim 2 wherein the angular separation of said convolutions of wire extending around said perimeter through said first angular segment is equal to the angular separation of said convolutions of wire extending through said second angular segment.

4. A toroidally wound deflection yoke as defined in claim 3 wherein said core is a ferrite core.

5. A toroidally wound deflection yoke as defined in claim 4 wherein said yoke includes a grooved end ring located at the front portion of said core, said grooves having an angular separation equal to said angular separation of said convolutions of wire wound around said core.

6. A toroidally would deflection yoke for a delta gun shadow mask color television picture tube for providing convergence of the beams in the comers of a raster displayed on said picture tube, comprising:

a toroidal core;

a first winding of conductors having a first angular separation from each adjacent conductor wound axially on said core and extending around said core;

at least a second winding of conductors having a second angular separation from each adjacent conductor wound axially on said core and extending around said core;

means for interconnecting a continuous portion of conductors contained within said first winding and a continuous portion of conductors contained within said second winding for forming each of a pair of horizontal and vertical deflection coils, the transverse cross-sectional conductor distribution of said horizontal and vertical coils being symmetrical about respective horizontal and vertical axes of said core said continuous portions of said first and second windings being selected to respectively extend around said core a predetermined distance for producing a magnetic field which provides convergence of the beams in the comers of said raster.

7. A toroidally wound deflection yoke for a delta gun color television picture tube, said yoke including horizontal and vertical coils wound on a toroidal core:

each of said coils comprising convolutions of conductors having a predetermined angular separation from adjacent conductors in a layer wound axially on and extending around said core, said conductors forming a first layer extending around said core for different angles for the respective vertical and horizontal coils measured from respective vertical and horizontal axes of symmetry defining quadrants of said core;

one of said coils further including a symmetrical portion in each of the four quadrants around said core, each portion including said angularly separated conductors in a second layer extending continuously over a first angle around said core from an axis of symmetry, a separation of said coil conductors extending continuously over a second angle, and angularly separated conductors extending continuously over a third angle, said first, second and third angles being contiguous; and

the other of said coils having a symmetrical portion in each of the four quadrants around said core, each portion including angularly separated conductors in said second layer extending, continuously around said core over a fourth angle from another axis of symmetry, and a portion tical coils wound in two layers on a toroidal core:

a first layer including conductors having a predetennined angular separation from each adjacent conductor extending continuously over a first angle around said core from a first axis of symmetry defining quadrants of said core for forming a portion of one of said vertical and horizontal coils in each of said quadrants, and conductors having a predetermined angular separation from each adjacent conductor extending continuously over a second angle around said core from a second axis of symmetry defining said quadrants for fonning a portion of the other of said vertical and horizontal coils in each of said quadrants;

a second layer including conductors having a predetermined angular separation from each adjacent conductor extending continuously over a first angle around said core from said first axis, having a separation between conductors over a second angle, and extending continuously for a third angle, said first, second and third angles being contiguous, for forming further portions of one of said vertical and horizontal coils, and conductors having a predetermined angular separation from each adjacent conductor extending continuously over a fourth angle around said core from said second axis and conductors extending continuously within said separation of conductors within said second angle for forming further portions of the other of said vertical and horizontal coils; and means for interconnecting said portions of said vertical and horizontal coils contained within said first and second layers.

10. A toroidally wound deflection yoke according to claim 9 wherein said one of said coils is a vertical deflection coil and the said other of said coils is a horizontal deflection coil.

. UNITED STATES PATEN'l OFFICE CERTIFICATE OF CORRECTION Patent No. 3,643,192 Dated Februarv 15, 1972 Inventor (S) Wayne Richard Chiodi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 31, after "mask" and before "tube" insert picture Column 3, line 44, that portion reading "Each conductor the" should read Each of the Column 4, line 10, that portionof the'equation reading "af6" should read afe line 68, that portion reading "seem" should read seen Column 5, line 16, after "and" and before "21d" insert wires line 34, that portion reading "exits" should read as exists Column 6, line 17, that portion reading "100" should read 110 Column 7, line 33, that portion of the equation reading "bM cM should read bM H (:M Column 8 line 68, that porti n readixg "would" should read wound Signed and sealed this 27th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents "ORM PO-105O (IO-69) USCOMM'DC SOS'IG-PGQ 5 U.S. GOVERNMENT PRINTING OFFICE: I969 0-355-334 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,643,192 Dated February 15 19 72 Inventor(s) Wayne Richard Chiodi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 31, after "mask" and before "tube" insert picture Column 3, line 44, that portion reading "Each conductor the" should read Each of the Column 4, line 10, that portion of the equation reading "afe" should read afS line 68, that portion reading "seem" should read seen Column 5, line 16, after "and" and before "21d" insert wires line 34, that portion reading "exits" should read as exists Column 6, line 17, that portion reading "100" should read 110 Column 7, line 33, that portion of the equation reading "bM cM should read bM H cM Column 8, line 68, that porti n readixg "would" should read wound Signed and sealed this 27th day or June 1972.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents ORM PO-105O (IO-69) USCOMM-DC 5037$-P59 h UrS GOVERNMENT PRINYING OFFICE: 1959 C3G6-33d 

1. A toroidally wound deflection yoke for a delta gun shadow mask color television picture tube for providing convergence of the beams in the corners of a raster displayed on said picture tube, comprising: a cylindrical core having the inside portion thereof flared to conform generally with a flared portion of said picture tube, a pair of horizontal and vertical windings wound toroidally around said core for dEflecting the electron beams of said tube upon energization of said windings, each of said vertical and horizontal windings comprising symmetrical convolutions of wire in each of the quadrants of said yoke, forming portions of said vertical and horizontal windings therein, said quadrants being defined by the vertical and horizontal axes of deflection, each of said portions of said vertical and horizontal windings in each of said quadrants comprising at least convolutions of wire having a first predetermined angular separation from each other extending continuously throughout a first angular segment along the perimeter of said core from a line of symmetry of said quadrant and convolutions of wire having a second predetermined angular separation from each other extending continuously throughout a second angular segment along said perimeter from said line of symmetry, said first and second angular segments being selected for producing a magnetic field which provides convergence of the beams in the corners of said raster.
 2. A toroidally wound deflection yoke as defined in claim 1 wherein said first and second angular segments are different whereby the conductor distribution density is higher in that portion of the quadrants wherein said first and second segments overlap than in that portion of the quadrants wherein said angles do not overlap.
 3. A toroidally wound deflection yoke as defined in claim 2 wherein the angular separation of said convolutions of wire extending around said perimeter through said first angular segment is equal to the angular separation of said convolutions of wire extending through said second angular segment.
 4. A toroidally wound deflection yoke as defined in claim 3 wherein said core is a ferrite core.
 5. A toroidally wound deflection yoke as defined in claim 4 wherein said yoke includes a grooved end ring located at the front portion of said core, said grooves having an angular separation equal to said angular separation of said convolutions of wire wound around said core.
 6. A toroidally would deflection yoke for a delta gun shadow mask color television picture tube for providing convergence of the beams in the corners of a raster displayed on said picture tube, comprising: a toroidal core; a first winding of conductors having a first angular separation from each adjacent conductor wound axially on said core and extending around said core; at least a second winding of conductors having a second angular separation from each adjacent conductor wound axially on said core and extending around said core; means for interconnecting a continuous portion of conductors contained within said first winding and a continuous portion of conductors contained within said second winding for forming each of a pair of horizontal and vertical deflection coils, the transverse cross-sectional conductor distribution of said horizontal and vertical coils being symmetrical about respective horizontal and vertical axes of said core said continuous portions of said first and second windings being selected to respectively extend around said core a predetermined distance for producing a magnetic field which provides convergence of the beams in the corners of said raster.
 7. A toroidally wound deflection yoke for a delta gun color television picture tube, said yoke including horizontal and vertical coils wound on a toroidal core: each of said coils comprising convolutions of conductors having a predetermined angular separation from adjacent conductors in a layer wound axially on and extending around said core, said conductors forming a first layer extending around said core for different angles for the respective vertical and horizontal coils measured from respective vertical and horizontal axes of symmetry defining quadrants of said core; one of said coils further including a symmetrical portion in each of the four quadrants around said core, each portion including said angularly separated conductors in a second layer extendiNg continuously over a first angle around said core from an axis of symmetry, a separation of said coil conductors extending continuously over a second angle, and angularly separated conductors extending continuously over a third angle, said first, second and third angles being contiguous; and the other of said coils having a symmetrical portion in each of the four quadrants around said core, each portion including angularly separated conductors in said second layer extending continuously around said core over a fourth angle from another axis of symmetry, and a portion of said angularly separated conductors contained within said second angle of separation of said conductors of the one of said coils.
 8. A toroidally wound deflection yoke according to claim 7 wherein said one of said coils is a vertical deflection coil and the other of said coils is a horizontal deflection coil.
 9. A toroidally wound deflection yoke for a delta gun color television picture tube, said yoke including horizontal and vertical coils wound in two layers on a toroidal core: a first layer including conductors having a predetermined angular separation from each adjacent conductor extending continuously over a first angle around said core from a first axis of symmetry defining quadrants of said core for forming a portion of one of said vertical and horizontal coils in each of said quadrants, and conductors having a predetermined angular separation from each adjacent conductor extending continuously over a second angle around said core from a second axis of symmetry defining said quadrants for forming a portion of the other of said vertical and horizontal coils in each of said quadrants; a second layer including conductors having a predetermined angular separation from each adjacent conductor extending continuously over a first angle around said core from said first axis, having a separation between conductors over a second angle, and extending continuously for a third angle, said first, second and third angles being contiguous, for forming further portions of one of said vertical and horizontal coils, and conductors having a predetermined angular separation from each adjacent conductor extending continuously over a fourth angle around said core from said second axis and conductors extending continuously within said separation of conductors within said second angle for forming further portions of the other of said vertical and horizontal coils; and means for interconnecting said portions of said vertical and horizontal coils contained within said first and second layers.
 10. A toroidally wound deflection yoke according to claim 9 wherein said one of said coils is a vertical deflection coil and the said other of said coils is a horizontal deflection coil. 